The main reason I don't believe in gods now is different from the reason I had when I stopped believing about nine years ago. Nine years ago, I would have merely said that the arguments for God were lacking. I am even less charitable today, because I don't think there's any reason to consider God as a hypothesis in the first place. We do have social reasons to talk about God, but as far as truth-seeking is concerned, the probability of God is so low that by even thinking about it we're tipping the scales.
This is not the argument I would use to try to persuade people of atheism. My way of thinking of it is too technical. And it advances a position that is far stronger than is socially necessary for an atheistic society. What does it matter to me whether you believe the probability of God is unimaginably low, or just extremely low?
But then, I'm not really in the business of directly persuading people to atheism in general. Just talking about stuff is more fun.
Generally, a good model for thinking about degrees of belief is to speak of Bayesian probabilities. You might start with "neutral" priors, such as God having a 50% chance to exist. Then you consider all the evidence and arguments for and against God, and modify the probability accordingly. An atheist would likely look at the evidence, and think that the problem of evil and problem of divine silence weigh heavily against the existence of God, and that none of the usual arguments in favor of god are effective. But under such an analysis, how low would you really rate the probability of God? I think you would rate it very low, but not unimaginably low.
I rate the probability of God even lower than that, basically because I go beyond the basic Bayesian analysis. I think assigning a 50% prior probability to God is already far too favorable.
As far as theories of the world go, the idea of God is extremely peculiar and narrow. The ideas of consciousness and intentionality are ordinary to us, because that's the kind of life that matter and evolution produce for us. But to theorize about consciousness and intentionality which exists prior to the laws of physics is very strange. And that's before even introducing our even more peculiar ideas of morality.
It reminds me when non-physicists think that quantum mechanics is so strange, that there must be something beyond quantum mechanics. It is true that quantum mechanics is strange, but strangeness is relative to our own experience in the world that emerges on large scales. What makes quantum mechanics strange is that it produces a world which looks entirely different on small and large scales.
Now it could very well be that there is something underneath quantum mechanics, and that quantum mechanics simply emerges from more fundamental rules. I think it likely, even. But why would we ever think that what's underneath would look similar to what's above? Whatever's under quantum mechanics will not look like classical physics, it will look even stranger than ever.
The idea of a god is basically the theory that what's at the very bottom (a god underlying the entire universe) is similar to what's at the very top (intelligence emergent from complex biological processes) even though the bulk of the middle looks entirely different. It doesn't make sense to even propose such a thing, and it makes all too much sense that we as humans would propose it anyway.
The other thing you may have noticed is that the existence of God is not at all obvious in our world. God is intangible, except in our minds where the same feelings could be caused by any number of things. The only miracles performed are unverifiable, and split across mutually contradictory religions. This would be overwhelming evidence against a god, except that theists have basically tailored their conception of god to avoid it.
Of course god is intangible. Of course god only touches our minds. Of course god is like us since he made us in his image. Of course god is leery of showing himself directly. As for the problem of evil, god is just too difficult for our minds to understand (but apparently familiar enough that we can have called god "good" in the first place).
With all these preconceptions built in, gods at least aren't completely eliminated by the evidence. But when you tailor the god hypothesis like that, you are basically making the god hypothesis even more specific and more strange than ever. As discussed in a previous post, this is basically an exploitation of the definition of evidence. By tailoring your theory just right, it is possible to find a theory which is "favored" by the evidence or at least not completely eliminated by it. But by doing so, you've ultimately chosen a theory which is more unlikely than ever.
Is there any evidence that could make me believe in a god? Probably--I mean, a complete change in every aspect of the universe would be fairly persuasive. But the problems with god as an idea come even before we talk about evidence.